Automatic (Self-Winding): A rotor on the movement keeps the watch powered by the motion on your wrist. The rotor transfers power to the mainspring which makes the watch go. If worn everyday, an automatic watch will run for decades (or until it breaks, or desperately needs a service). The majority of automatic movements have a power reserve of 38 to 48 hours.
The rotor was first invented in 1770 by Abraham-Louis Perrelet, but the invention was shelved since it could not effectively charge a pocket watch. When wristwatches became popular in the 1900s, the self-winding rotor began to make a lot more sense.
Manual Wind: A manual wind watch must be wound every day by the crown in order to run. Even with that inconvenience, they are still produced by the major houses in Switzerland. Some of the most beautiful pieces made today are manual wind, and you actually won't find many value or budget manual winds (but they exist!). With exhibition backs becoming very common, it's nice to view the active movement without a rotor in the way.
Quartz: The quartz movement became common for watches in the late 70s. At first they commanded high prices, but a decade later you could find one at Target for $10, and it kept better time than your Patek Philippe. The quartz movement is powered by a battery and need little maintenance except for a battery swap every year or so.
Water resistance is normally expressed in meters. This rating is only theoretical and refers to the depth that a watch will keep water out if the watch and water are both motionless. These conditions never really exist in real life because the user's arm movement dramatically increases the pressure on the watch, along with the water moving itself. The chart below should help you understand how deep you can really go with your watch.
Measurement Units: 1 meter is approximately 3.3 feet 10 meters is approximately 1 ATM (atmosphere) or 1 Bar
PADI (Professional Association of Diving Instructors) states Dives in excess of 132ft (40m) can only be undertaken by divers who have experience at same depth to a maximum of 165ft (50m). A full oxygen tank won't even allow an experienced diver to stay 10 minutes at 50 meters... and yet, you really need a watch resistant to "200 meters" to do that. A round case and screwdown crown are essential for that resistance.
Watches should generally not be put in a sauna or a hot tub since the exposure to heat can easily make the gaskets lose their shape and ability to keep water out... Many people have reported enjoying a hot tub many times with their watch, and not had any problems. Just don't jump into the cold pool afterwards!
It is also generally advised that watches should not be worn in the bath/shower.
The soap suds reduce the surface tension of the rubber gasket in the watch, which allows water to get in. The soap can also damage the seal itself. Again, many people shower with their watches with no issues, just avoid getting soap on it.
A chronograph is a watch that has a stopwatch function. It will have two or three additional registers. The simplest chronographs have a register for 30 minutes, and a center-mounted second hand. The popular ETA Valjoux 7750 times up to 12 hours. Most quartz chronographs also time tenths of a second, something a mechanical can not easily do (and something most people don't need).
A chronometer is watch that has passed a series of tests, and is a superior timekeeper. To become a chronometer, the watch movement must pass 15 days of severe tests. The accuracy of the movement is checked in 5 different positions at varied temperatures. This simulates conditions under which the watch might be worn. The watch must average between +6 and -4 seconds per day in order to earn the certification.
If a watch is described simply as a "Chrono", it is generally safe to assume it is a chronograph.
Sapphire, Mineral, and Plexiglas (typically called plastic or acrylic).
Sapphire crystals are the most expensive and the most scratch resistant. It can only be scratched by diamonds and other surfaces with a mineral hardness of 10. They are generally over $100 to replace and basically impossible to buff any scratches out. Since they are so hard, they are more likely to shatter on heavy impacts than a plastic crystal. As more consumers understand the durability of sapphire, more come to expect it on their watches. The vast majority of modern Swiss watches (and the watches Bernard Watch sells) utilize a sapphire crystal.
Plastic/acrylic crystals are the least expensive and commonly found on vintage watches and select modern watches. These crystals scratch easily, however they are cheap to replace and easy to buff scratches. Plastic crystals offer a "warmer" appeal. Reissues like the Tag Heuer Monaco are often fitted with acrylic crystals to maintain the appeal of the original.
Mineral crystals are between plastic and sapphire in cost and scratch resistance. It is virtually impossible to tell the difference between mineral and sapphire without taking a steel knife to the crystal to test it (not recommended!). Mineral crystals are more commonly found on non-Swiss watches. Bernard Watch sees very very FEW mineral crystals.